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Rash from poison ivy. Many people develop an itchy rash that causes lines or streaks that look like this.

Poison ivy, oak and sumac: Overview

Many people get a rash from poison ivy, poison oak, and poison sumac. This rash is caused by an oil found in the plants. This oil is called urushiol (you-ROO-shee-all).

The itchy, blistering rash often does not start until 12 to 72 hours after you come into contact with the oil.

The rash is not contagious and does not spread. It might seem to spread, but this is a delayed reaction.

Most people see the rash go away in a few weeks. If you have a serious reaction, you need to see a doctor right away. Swelling is a sign of a serious reaction — especially swelling that makes an eye swell shut or your face to swell.

If you have trouble breathing or swallowing, go to an emergency room immediately.

Image used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.

Poison ivy, oak and sumac: Signs and symptoms

What you see and feel on your skin is caused by urushiol (you-ROO-shee-all). Urushiol is the oil in poison ivy, oak, and sumac. You find this oil in all parts of the plants — the leaves, stems, and even the roots. Within minutes of contact with urushiol, the skin starts to absorb it. But you don't feel this. And you don't see a rash right way.

If this is your first contact with urushiol, you may not see a rash. Or it may take a week for the rash to appear. The rash also can appear within hours or a few days. If you have a reaction to the oil, you can have these signs (what you see) and symptoms (what you feel):

Itchy skin.

Redness or red streaks.

Hives.

Swelling.

An outbreak of small or large blisters, often forming streaks or lines.

Crusting skin (after blisters burst).

The rash is very itchy and can appear on any part of the body. The rash can continue to appear on new parts of the body when:

Other parts of the body touch the oil.

You spread the oil on your skin by touching other parts of your body.

You cannot give the rash to someone else. Even if the person touches the rash or the fluids in the blisters, the person cannot get the rash. The person has to touch the oil to get the rash.

Image used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.

Poison ivy, oak and sumac: Who gets and causes

Who gets this rash?

Most people (85 percent) develop a rash when they get urushiol on their skin. The first time you get this oil on your skin, you may not get a rash. The next time this oil gets on your skin you can become sensitive to it. Once you are sensitive to it, a rash appears. About 15 percent of people do not become sensitive to this oil and never develop a rash.

Adults who had rashes as a child often find that they are less sensitive as adults. They may completely lose their sensitivity and never get another rash when the oil touches their skin. Adults who never had a rash as a child may become sensitive to the oil.

What causes this rash?

There are 3 ways to get this rash:

Direct contactBy touching poison ivy, poison oak, or poison sumac, you can get a rash. Every part of these plants — the leaves, stems, roots, and flowers — contains the oil.

Indirect contact
Urushiol can stick to almost anything. If you touch a pet's fur, gardening tool, or sports equipment that has the oil on it, you can get a rash. Dogs and other animals do not get this rash. Only people get this rash.

Airborne contact
Burning these poisonous plants releases particles of urushiol into the air. These airborne particles can land on the skin.

It is not possible to get this rash from touching someone who has the rash. The skin absorbs the oil too quickly. You cannot get a rash from getting the fluid in the blisters on your skin.

Poison ivy, oak and sumac: Diagnosis and treatment

If you have any of the following symptoms, go to the emergency room right away:

Trouble breathing or swallowing.

Rash covers most of your body.

You have many rashes or blisters.

Swelling, especially if an eyelid swells shut.

Rash develops anywhere on your face or genitals.

Much of your skin itches or nothing seems to ease the itch.

How do dermatologists diagnose poison ivy?

A dermatologist can usually look at the rash and tell you whether your rash is due to poison ivy, oak, or sumac.

How do dermatologists treat poison ivy?

If you have a serious reaction, you will likely need prescription medicine. Your dermatologist may prescribe a steroid ointment that you can apply to the skin. To treat a severe case, a strong medicine like prednisone may be necessary.

If you have an infection, your dermatologist may prescribe an antibiotic. You likely have an infection if you develop a fever or have pus, pain, swelling, and warmth around the rash.

If you are not sure what caused your rash, you should see a dermatologist. Rashes appear on the skin for many reasons.

Outcome

A rash from poison ivy, oak, or sumac usually lasts 1 to 3 weeks. Most rashes go away without treatment. While your skin heals, it often itches.

Poison ivy, oak and sumac: Tips for managing

A rash from poison ivy, poison oak or poison sumac is caused by an oil found in these plants called urushiol (you-ROO-shee-all). When this oil touches your skin, it often causes an itchy, blistering rash.

Most people can safely treat the rash at home. However, if you experience any of the following symptoms, go to the emergency room right away.

If you have any of the following, go to the emergency room right away:

You have trouble breathing or swallowing.

The rash covers most of your body.

You have many rashes or blisters.

You experience swelling, especially if an eyelid swells shut.

The rash develops anywhere on your face or genitals.

Much of your skin itches, or nothing seems to ease the itch.

If you do not have the above symptoms, the rash appears on a small section of your skin, and you are absolutely certain that your rash is due to poison ivy, poison oak, or poison sumac, you may be able to treat the rash at home.

To treat a rash from poison ivy, poison oak, or poison sumac and help stop the itch, dermatologists recommend the following:

Immediately rinse your skin with lukewarm, soapy water. If you can rinse your skin immediately after touching poison ivy, poison oak, or poison sumac, you may be able to rinse off some of the oil. If not washed off, the oil can spread from person to person and to other areas of your body.

Wash your clothing. Thoroughly wash all of the clothes you were wearing when you came into contact with the poisonous plant. The oil can stick to clothing, and if it touches your skin, it can cause another rash.

Wash everything that may have the oil on its surface. Besides clothing, the oil from poison ivy, poison oak, and poison sumac can stick to many surfaces, including gardening tools, golf clubs, leashes and even a pet’s fur. Be sure to rinse your pet’s fur, and wash tools and other objects with warm, soapy water.

Do not scratch, as scratching can cause an infection.

Leave blisters alone. If blisters open, do not remove the overlying skin, as the skin can protect the raw wound underneath and prevent infection.

Take short, lukewarm baths. To ease the itch, take short, lukewarm baths in a colloidal oatmeal preparation, which you can buy at your local drugstore. You can also draw a bath and add one cup of baking soda to the running water. Taking short, cool showers may also help.

Consider calamine lotion or hydrocortisone cream. Apply calamine lotion to skin that itches. If you have a mild case, a hydrocortisone cream or lotion may also help.

Apply cool compresses to the itchy skin. You can make a cool compress by wetting a clean washcloth with cold water and wringing it out so that it does not drip. Then, apply the cool cloth to the itchy skin.

Consider taking antihistamine pills. These pills can help reduce itching, however use with caution. You should not apply an antihistamine to your skin, as doing so can worsen the rash and the itch.

If your rash is not improving after seven to 10 days, or you think your rash may be infected, see a board-certified dermatologist. A dermatologist can treat your rash and any infection and help relieve the itch.

Poison ivy: This plant grows as a vine (pictured) in some areas of the United States. In other areas, it is a shrub.

Prevent a rash from poison ivy, oak, or sumac

There are two ways to prevent a rash:

Avoid these poisonous plants.

Protect your skin.

The following explains how you can identify these plants so you can avoid them and how to protect your skin when you cannot avoid these plants.

What poison ivy looks like

Each leaf has 3 small leaflets.

It grows as a shrub (low woody plant) in the far Northern and Western United States, Canada, and around the Great Lakes.

It grows as a vine in the East, Midwest, and South of the United States.

In spring, it grows yellow-green flowers.

It may have green berries that turn off-white in early fall.

Poison oak: This plant grows as a vine (pictured) in some areas of the United States. In other regions, it grows as a shrub.
What poison oak looks like:

Each leaf has 3 small leaflets.

It most often grows as a shrub.

It can grow as a vine in the Western United States.

It may have yellow-white berries.

What poison sumac looks like:

Each leaf has a row of paired leaflets and another leaflet at the end.

It grows as a tall shrub or small tree.

In the Northeast and Midwest, it grows in standing water in peat bogs.

In the Southeast, it grows in swampy areas.

Often, the leaves have spots that look like blotches of black paint. These spots are urushiol, which when exposed to air turn brownish black. Before urushiol hits the air, it is clear or a pale yellow. Poison sumac: This plant has 7 to 13 leaflets on each leaf. It grows in standing water as a tall shrub or small tree.

It may have yellow-white berries.

How to protect your skin from poison ivy, oak, and sumac

Sometimes you cannot avoid these plants. When you find yourself in this situation, there are some precautions you can take:

Use a skin-care product called an ivy block barrier. This helps prevent the skin from absorbing the oil (urushiol), which causes the rash. These products usually contain bentoquatam. You can buy these products without a prescription. Be sure to apply the block before going outdoors.

Wear long pants, long sleeves, boots, and gloves. Even when you apply an ivy block barrier that contains bentoquatam, you need to cover your skin with clothing.

If you find yourself in an area with poison ivy, oak, or sumac, it helps to know the following:

All parts of these plants contain urushiol. The leaves, the stems, and even the roots contain urushiol. Touching any part of the plant can cause an allergic reaction.

Touching anything that has urushiol on it can cause an allergic reaction. You can have an allergic reaction from touching gardening tools, sporting equipment, and even a pet’s fur.

Burning these plants releases urushiol into the air. You can have an allergic reaction if airborne particles land on your skin.

If you get a rash from poison ivy, poison oak, or poison sumac, you can usually treat the rash at home. If you have a serious reaction, seek immediate medical care by going to the emergency room or calling 911.

Images used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.